An artificial protein cage made from a 12-membered ring

Area of Science:

• Biophysics
• Structural Biology
• Protein Engineering

Background:

• Artificial protein cages offer potential in medicine, particularly for vaccines and drug delivery.
• TRAP-cages are adaptable protein structures assembled from ring-like subunits, allowing control over disassembly.
• Previous TRAP-cages used 11-monomer rings (hendecamers), posing challenges for forming regular polyhedral structures.

Purpose of the Study:

• To investigate the error tolerance limits in protein cage formation.
• To explore the assembly of TRAP-cages using a 12-monomer ring (dodecamer) variant.
• To gain insights into the fundamental rules governing protein cage assembly.

Main Methods:

• Construction and structural analysis of a novel TRAP-cage using dodecameric rings.
• Cryo-electron microscopy (cryo-EM) to determine the cage's high-resolution structure.
• Comparison of experimental structures with theoretical models and existing TRAP-cage data.

Main Results:

• A stable, apparently regular protein cage was successfully formed using 12-monomer TRAP rings.
• The dodecameric cage structure provides insights into how protein assemblies accommodate geometric constraints.
• The study demonstrates that TRAP-cages can tolerate specific levels of structural error during formation.

Conclusions:

• Protein cages can be formed from subunits with varying numbers of monomers, expanding design possibilities.
• Understanding error tolerance is crucial for predicting and designing novel protein cage architectures.
• This work lays the foundation for engineering new TRAP-cages with tailored properties for biomedical applications.